Solar storms stranding North Sea whales

The deaths of these majestic creatures had remained an unsolved mystery for over a year. Now scientists think they’ve hit on why the number of strandings has recently increased

In early 2016, 29 whales were devastatingly stranded and died on beaches across Europe in under a month. The reason why has remained a tragic mystery for over a year, but a recent report published in the International Journal of Astrobiology suggests solar storms – those also responsible for creating the Northern Lights – may have been the cause.

Between 8 January and 4 February last year, 29 seemingly healthy, male sperm whales were washed up on beaches in the the southern region of the North Sea. The first was found stranded in Germany and subsequently more were beached across The Netherlands, France and the east coast of England.

Initial reports at the time believed the whales got into trouble after hunting shoals of squid which led them into shallow waters or that they had swallowed polluting ocean plastics which ultimately caused their deaths. However, the suggestion that indigestible plastics were the cause was later dismissed as highly unlikely because not all of the whales had plastic in their stomachs, nor were there particularly significant amounts in those that did. Similarly, there were questions surrounding the squid-hunting hypothesis because squid are not normally found in such shallow waters either. However, this new research has provided a plausible and likely explanation for the whales’ deaths.

Whales use the Earth’s geomagnetic field to navigate their way through the oceans. Large solar storms that took place in December 2015 created geomagnetic disturbances which have been known to confuse and disorientate migratory animals such as birds and bees. The study suggests the same happened with these relatively young bull whales, which were inexperienced in recognising the disturbances and knowing how to navigate their way using alternative methods.

Female sperm whales and their calves only live in lower latitude waters (between 40°N and 40°S), but once male bulls reach independence at around ten to 15 years, they migrate further north in so-called ‘bachelor groups’. Older more experienced males travel alone and so the younger, ‘naïve’ males are left to fend for themselves. Whales are believed to possess a magnetic sense whereby they navigate their migration route using the Earth’s geomagnetic alignments. These geomagnetic ‘maps’ are very different from sea depth maps and so they may not recognise that they are entering shallow waters if they only follow their geomagnetic senses. Older bulls are experienced in migratory patterns and are thought to use other navigation methods, such as sonar clicks, if they realise their orientation is wrong.

‘Lulu’ washed up on the shores of Scotland earlier this year, originally thought to have been killed from plastic pollutants in the waters (Image: John Bowler/RSPB Scotland)

One known migration route of sperm whales passes west of the UK and through the Faroe-Shetland Channel into the Norwegian Sea where there is an abundance of squid. It is understood this bachelor group had taken this route because of the squid content found in their stomachs during the autopsies. But rather than pass back through the Faroe-Shetland Channel on their route back to the lower latitudes, it was here the whales are believed to have gotten lost and instead headed southward into the North Sea.

On 20 and 31 December 2015, magnetometer readings from the Sølund station in Norway detected changes in the magnetic field from solar activity. The activity temporarily altered the geomagnetic map by up to 460km in the region around Shetland and essentially disguised a geomagnetic boundary that prevents the whales travelling into the North Sea. ‘The whales thought that they were on the right side (north) of the “thought barrier”, when they were actually on the wrong (south) side due to the solar storm,’ explains the research paper.

Whales can often swim in the wrong direction for a day or two when they become lost or disorientated, but usually correct their course without any major problems. Unfortunately, once they enter shallow waters it is very unlikely to result in a positive outcome, particularly in the North Sea where the bed is typically mud or sand. The whales cannot use the echoes from their sonar clicks to navigate in this terrain and so they suffer from respiratory failure in the shallows with their lungs eventually collapsing.

These solar storms are also responsible for the natural phenomena the Aurora Borealis (otherwise known as the Northern Lights) and the ones that occurred in December 2015 were so large in the region they could be seen from the Caithness coast in northern Scotland, adding further support to the study. NASA is also conducting research into the possibility of solar storms causing animal beachings.

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